Respiration-induced attenuation artifact at PET/CT: technical considerations.

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiology

Background:

• Combined positron emission tomographic/computed tomographic (PET/CT) scanners utilize CT data for PET image attenuation correction.
• Accurate attenuation correction is crucial for reliable PET image quantification and interpretation.

Purpose of the Study:

• To evaluate the impact of CT data acquisition during different respiratory phases (maximum inspiration, normal expiration) on PET image quality.
• To compare CT-based attenuation correction with conventional methods in PET/CT imaging.

Main Methods:

• Eight cancer patients underwent PET/CT scans.
• Transmission scans were acquired using conventional attenuation correction and CT during maximum inspiration and normal expiration.
• Image quality was assessed visually, and fluorine-18 activity was measured in lung and myocardial regions of interest.

Main Results:

• A significant decrease in measured fluorine-18 activity was observed in PET images corrected with CT data acquired during maximum inspiration compared to conventional correction or CT during normal expiration (P =.0001).
• Deep inspiration during CT scanning led to a noticeable deterioration in final PET image quality.

Conclusions:

• Acquisition of CT data during deep inspiration for attenuation correction in PET/CT can significantly degrade image quality and affect quantitative accuracy.
• Respiratory gating or patient coaching to maintain a consistent breathing pattern during CT acquisition is recommended for optimal PET/CT imaging.